Angry outbursts may up heart attack risk

“Having a hot temper may increase your risk of having a heart attack or stroke, according to researchers,” BBC News reports.

Research has found that people prone to attacks of rage have a higher risk of a experiencing a serious cardiovascular event, such as a heart attack or stroke.

Researchers conducted a systematic review, collating the findings of previous studies. Their results suggest that outbursts of anger increase the risk of a serious cardiovascular event by almost fivefold (4.74, to be exact).

However, there are a few flaws to the research. The most pertinent is that some of the studies included in the review collected information after the cardiovascular event occurred. This type of information gathering is prone to what is known as recall bias.

For example, if a person has a heart attack in the afternoon, they may be more likely to remember the driver that “cut them up” at a roundabout that morning than someone who didn’t experience a cardiovascular event.

There could also be other factors that link anger and cardiovascular events and are responsible for the association seen.

Finally, no studies used in the analysis looked at the general population and whether anger levels increased their likelihood of having a cardiovascular event. The researchers said the results “should not be assumed to indicate the true causal effect of anger episodes on cardiovascular events”.

Where did the story come from?

The study was carried out by researchers from Harvard Medical School, Harvard School of Public Health and New York-Presbyterian Hospital/Weill Cornell Medical Centre, New York. It was funded by the US National Institutes of Health.

The results of the research were well reported by the UK media. They put the small risk of a cardiovascular event into its proper context, while also pointing out that unresolved anger can impact on a person’s health.

What kind of research was this?

This was a systematic review that aimed to find out whether episodes of anger are linked to a short-term risk of experiencing a cardiovascular event, such as a heart attack, stroke or disturbances in heart rhythm.

Systematic reviews are the best way of determining what is known about a topic.

However, it’s worth considering that this systematic review contained case-crossover studies. In these, information on whether the participants were angry or calm was obtained during two different periods of time: immediately before the cardiovascular event and at an earlier time.

The level and frequency of anger just prior to a cardiovascular event was then compared to the level of anger in the same people at an earlier time.

Although case-crossover studies can show a link between two things, there could be other factors at play. In this instance, there could be numerous reasons for the link between anger and cardiovascular events. As mentioned previously, case-crossover studies are also prone to recall bias.

What did the research involve?

The researchers searched databases of literature to identify all studies that had evaluated whether outbursts of anger are linked to a short-term risk of heart attack, stroke or disturbances in heart rhythm. For studies to be included, they had to evaluate triggers occurring within one month of the cardiovascular event.

The results of these studies were then combined to see if anger was associated with the short-term risk of one of these events. The researchers calculated incidence rate ratios, which compared the number of cardiovascular events in the two hours following outbursts of anger with the number of cardiovascular events that weren’t preceded by anger.

What were the basic results?

The researchers identified and included nine case-crossover studies:

four of anger outbursts and heart attack/acute coronary syndrome (various heart conditions including heart attack and unstable angina caused by reduced blood flow to a part of the heart)

two of anger outbursts and ventricular arrhythmia (abnormal heart rhythm)

The studies were substantially different – they were performed in different countries and collected information about anger episodes differently.

The researchers found there was a 4.74 times higher risk of heart attack/acute coronary syndrome in the two hours following outbursts of anger compared to normal (95% Confidence Interval [CI] 2.50 to 8.99).

The risk of having a stroke was not significantly higher in the two hours following anger compared to normal (95% CI 0.82 to 16.08).

The one study that assessed the risk of ruptured intracranial aneurysms found a statistically significant increased risk in the hour following an outburst of anger (95% CI 1.59 to 24.90).

The two studies that analysed whether outbursts of anger are associated with ventricular arrhythmia were too different to be combined, but both studies found that anger episodes significantly increase a person’s risk.

Researchers point out that although the relative risks of cardiovascular events following an anger outburst are large, the impact on an individual’s absolute risk of a cardiovascular event may be small.

This is because the initial baseline risk of experiencing a cardiovascular event is small.

That said, when we consider the increased risk at population levels, it seems that frequent outbursts of anger do take a toll on the public's health.

They calculate, based on the combined estimate of a 4.74 times higher rate of heart attack/acute coronary syndrome in the two hours following outbursts of anger, that:

one episode of anger per month would result in one excess cardiovascular event per 10,000 people per year at low (5%) 10-year cardiovascular risk

one episode of anger per month would result in four excess cardiovascular events per 10,000 people per year at high (20%) 10-year cardiovascular risk

five episodes of anger per day would result in approximately 158 excess cardiovascular events per 10,000 per year for people at low 10-year cardiovascular risk

five episodes of anger per day would result in approximately 657 excess cardiovascular events per 10,000 per year among people at high 10-year cardiovascular risk

How did the researchers interpret the results?

The researchers concluded that, “there is a higher risk of cardiovascular events shortly after outbursts of anger”.

Conclusion

This systematic review found there is an increased risk of cardiovascular events, including heart attack and disturbances in heart rhythm, shortly after outbursts of anger.

This is based on results from nine case-crossover studies. In these, information on feelings of anger in the period before the cardiovascular event, as well as an earlier period, were collected retrospectively. The risk of having a cardiovascular event after an episode of anger was then calculated.

The researchers point out several limitations to their review, including the fact that:

participants were asked to remember angry outbursts hours or days after the cardiovascular event – in one of the studies this was two weeks later. It’s possible that this could be inaccurate if someone has just experienced an unpleasant or life-threatening event. They were also asked to recall periods of anger in the preceding 6-12 months. There may also be selective recall, forgetting or being unaware of the frequency of other angry outbursts. In one study, people were asked to recall any angry outbursts on the same day and time of the previous week, which may have been difficult to accurately remember

the studies used different methods to record outbursts of anger. Some studies recorded this using an interview, while others used a questionnaire – these methods can result in people responding differently

A further limitation is that the studies only included people who have suffered from a cardiovascular event. None of them looked at the general population and made any between the number of angry outbursts and risk of cardiovascular event.

Although case-crossover studies can demonstrate a link, there could be other factors that link anger and cardiovascular events and are responsible for the association seen. The researchers concluded that “the results should not be assumed to indicate the true causal effect of anger episodes on cardiovascular events”.